EP0774673B1 - Système de transmission et réception - Google Patents

Système de transmission et réception Download PDF

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Publication number
EP0774673B1
EP0774673B1 EP96118404A EP96118404A EP0774673B1 EP 0774673 B1 EP0774673 B1 EP 0774673B1 EP 96118404 A EP96118404 A EP 96118404A EP 96118404 A EP96118404 A EP 96118404A EP 0774673 B1 EP0774673 B1 EP 0774673B1
Authority
EP
European Patent Office
Prior art keywords
identification code
signal
transmitter
random number
receiver device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP96118404A
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German (de)
English (en)
Other versions
EP0774673A2 (fr
EP0774673A3 (fr
Inventor
Sadao Tokai-Rika-Denki-Seisakusho K.K. Kokubu
Hisashi Tokai-Rika-Denki-Seisakusho K.K. Aoki
Takashi Tokai-Rika-Denki-Seisakusho K.K. Mizuno
Shinichi Tokai-Rika-Denki-Seisakusho K.K. Koga
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tokai Rika Co Ltd
Original Assignee
Tokai Rika Co Ltd
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Publication date
Priority claimed from JP29808795A external-priority patent/JPH09139985A/ja
Priority claimed from JP30261195A external-priority patent/JPH09149480A/ja
Application filed by Tokai Rika Co Ltd filed Critical Tokai Rika Co Ltd
Publication of EP0774673A2 publication Critical patent/EP0774673A2/fr
Publication of EP0774673A3 publication Critical patent/EP0774673A3/fr
Application granted granted Critical
Publication of EP0774673B1 publication Critical patent/EP0774673B1/fr
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R25/00—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles
    • B60R25/01—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles operating on vehicle systems or fittings, e.g. on doors, seats or windscreens
    • B60R25/04—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles operating on vehicle systems or fittings, e.g. on doors, seats or windscreens operating on the propulsion system, e.g. engine or drive motor
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
    • G07C2009/00388—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks code verification carried out according to the challenge/response method
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
    • G07C2009/0042—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks the transmitted data signal containing a code which is changed
    • G07C2009/00476—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks the transmitted data signal containing a code which is changed dynamically
    • G07C2009/005—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks the transmitted data signal containing a code which is changed dynamically whereby the code is a random code
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C2009/00579—Power supply for the keyless data carrier
    • G07C2009/00603—Power supply for the keyless data carrier by power transmission from lock
    • G07C2009/00611—Power supply for the keyless data carrier by power transmission from lock by using inductive transmission
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
    • G07C2009/00753—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys
    • G07C2009/00769—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means
    • G07C2009/00777—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means by induction

Definitions

  • the present invention relates to a transmitter-receiver system, including a device having a transponder function of sending back an answer signal upon receiving an enquiry signal and a power signal.
  • a transmitter-receiver system including a device having a transponder function of sending back an answer signal upon receiving an enquiry signal and a power signal.
  • an interrogator and a responder exchange enquiry signals and answer signals in response thereto and, more particularly, the responder varies or scrambles the answer signal to be transmitted therefrom.
  • Such an ignition key is provided with a transmitter-receiver device contained in the key bow, and the transmitter-receiver device receives a power signal and an enquiry signal from an outside source, and sends back an answer signal that includes a pre-stored identification code.
  • the motor vehicle is equipped with a transmission-reception ECU that serves as an interrogator.
  • the transmission-reception ECU when an ignition key as described above is inserted in the ignition keyway and turned to the ON or ACC position, transmits the power signal and the enquiry signal to the ignition key, and receives the answer signal from the transmitter-receiver device of the ignition key, and then permitting the engine to start by the ignition key only when the identification code included in the answer signal agrees with a predetermined identification code.
  • the transponder function of the conventional transmitter-receiver devices is normally implemented by hard logic, resulting in fixed identification codes. Since fixed identification codes are relatively easy to copy, the conventional art is unable to sufficiently safeguard privacy or protect against theft.
  • the enciphering of identification codes is one measure to address this security problem.
  • the encipherment of the identification codes is not expected to significantly improve the privacy function.
  • the employment of a cryptosystem will complicate the hardware construction, increasing costs.
  • the hardware construction that is, the enciphering method and the code format are unchangeable, resulting in a singularly fixed cryptographic procedure. Therefore, if different ciphers are to be employed for different car makers or different destination markets, it becomes necessary to prepare different hardware constructions for individual transmitter-receiver devices, thus degrading working efficiency in production.
  • Japanese patent application laying-open No. HEI-7-18428 proposes a so-called rolling code method that sequentially changes the identification code for each answer signal transmission from the transmitter-receiver device.
  • this method cyclically produces answer signals that have the same identification code, and the number of identification codes that can be set in is limited. If anyone deciphers and copies the identification codes, that person will very likely be able to start the engine using the deciphered identification codes. This method thus fails to sufficiently enhance the security against motor vehicle theft.
  • a known transmitter-receiver device in the form of a wireless key is disclosed in US 5,376,932.
  • the device comprises respective circuits to demodulate a received modulated carrier and restore a signal representing the information emitted by an outside source and processing circuits generating a second signal, representative of the information to be emitted.
  • the second signal causes a variation in the impedance of a resonant circuit by means of another circuit, so that the information is thus transmitted.
  • This circuit comprises: a resonance circuit, capable of receiving electromagnetic signals; a power circuit for rectifying and smoothing a power signal supplied through the resonance circuit from an external antenna when the external antenna is electromagnetically coupled with the resonance circuit, the power circuit having a first time constant; a microcomputer powered by output AC from the power circuit; a detector circuit, having a second time constant which is lower than the first time constant of the power circuit, and which, when the resonance circuit is electromagnetically coupled with the external antenna, discriminates an enquiry signal supplied together with a power signal through the resonance circuit from the external antenna, and outputs the enquiry signal to the microcomputer; storing means for storing an identification code; and a modulating circuit that operates to transmit the answer signal by changing an impedance of the resonance circuit, wherein upon receiving the enquiry signal through the detector circuit, the microcomputer generates an altered identification code using the identification code read from the storing means, and controls transmission of an answer signal through the resonance circuit by operating the modulating circuit in a mode corresponding to the altered identification code.
  • US 4,509,093 discloses a transmission-reception system comprising: an interrogator that transmits an enquiry signal; and a responder that, upon receiving the enquiry signal from the interrogator, responds to the enquiry signal by sending back to the interrogator an answer signal including a pre-stored identification code, the interrogator transmitting random number data together with the enquiry signal, and determining whether the answer signal sent back from the responder matches a predetermined answer by calculation based on random number data and the identification code stored in the interrogator.
  • the responder changing the bit length of the stored identification code on the basis of the random number data from the interrogator and a predetermined calculation, and sending back an answer signal including the thus-changed identification code.
  • a predetermined rule is applied to a prestored identification code on the basis of the random number data, the random number being indicated as x, the rule being a real function including a 4th root function multiplied by a constant plus a further constant, wherein the first or second constant of that rule shall be interpreted as being equivalent to the prestored identification code of the present application.
  • Power supply for the component parts of the key unit can be of any suitable kind, such as a battery or the like. A remote powering of the key unit by a power signal transmitted from the lock unit is not intended.
  • US 5,055,701 discloses a keyless entry system comprising a portable transmitter and a control system for controlling a locking mechanism.
  • the control system
  • US 5,055,701 discloses a keyless entry system comprising a portable transmitter and a control system for controlling a locking mechanism.
  • the control system transmits a request code comprising a random number.
  • the random code is converted into a new particular code in cooperation with an identification code stored in memory.
  • the control system compares the particular code signal with the user particular code signal to activate the locking mechanism to lock or unlock a door when the two particular code signals are coincident with each other.
  • an identification code is transmitted, together with a random signal, from a fixed side to a portable side.
  • the signals are split whereafter the random signal is converted, by use of a specific code signal stored in the portable part, into a particular code signal which is transmitted to the fixed part of the system.
  • the fixed system the same procedure is executed so as to convert a particular code signal from the random signal which was, together with the identification code, transmitted to the portable part, and a specific code signal stored in the fixed part.
  • the present invention is intended to solve the above-stated and other problems in the art. It is an object of the invention to provide a transmitter-receiver device that improves key-signed privacy without complicating hardware construction or increasing production costs, and that is flexible to changes in the transmission signal enciphering method of the cipher code format.
  • a transmitter-receiver device In a transmitter-receiver device according to claim 1, an enciphered answer signal is transmitted in response to an enquiry signal.
  • the privacy safeguards will be improved.
  • the transmitter-receiver device of the invention is able to perform encipherment as desired without requiring complicated hardware construction while achieving a significant improvement in security.
  • the enciphering method or the like can be changed simply by changing the storage content of the microcomputer, the construction allows various cryptographic procedures to be used, eliminating the need to prepare different hardware constructions for individual transmitter-receiver devices. As a result, the working efficiency in production can be improved and costs can be reduced.
  • a data-reloadable nonvolatile memory as the storing means so that the identification code can be changed.
  • This preferred construction facilitates the setting and changing of the identification code format, improving the privacy function and increasing the degrees of freedom in design.
  • the storing means becomes able to be used as a storage for other useful data.
  • the transmitter-receiver device becomes more convenient to use.
  • the responder upon receiving an enquiry signal transmitted together with random number data from the interrogator, changes the bit length of the pre-stored identification code on the basis of the random number data received from the interrogator and the predetermined calculation, and sends back an answer signal including the thus-changed identification code.
  • the interrogator determines whether the answer signal is proper by the calculation based on the random number data transmitted to the responder and the identification code stored in the interrogator.
  • the system of the invention considerably improves security with regard to the answer signals from the responder, compared with the conventional method in which a plurality of identification codes sequentially cycle.
  • the responder be constructed to encipher the stored identification code by a predetermined cryptosystem, change the bit length of the enciphered identification code on the basis of the random number data received from the interrogator and the predetermined calculation, and send back an answer signal including the thus-changed identification code. Since this preferred construction performs double-encipherment of the identification, security with regard to the answer signals from the responder is remarkably improved.
  • the responder be constructed to change the bit length of the identification code on the basis of the random number data received from the interrogator and the predetermined calculation, and then encipher the thus-changed identification code by a predetermined cryptosystem, and send back an answer signal including the enciphered identification code. Since this preferred construction also performs double-encipherment of the identification, the privacy ability with regard to the answer signals from the responder is remarkably improved.
  • Fig. 1 illustrates an electrical construction of a transmitter-receiver device 2 (corresponding to a responder according to the invention) contained in the bow of an ignition key 1 shown in Fig. 3.
  • the transmitter-receiver device 2 has a microcomputer 3 as a significant component. Upon receiving a power signal and an enquiry signal from an outside source, transmitter-receiver device 2 responds to the enquiry signal by sending back an answer signal described below. The detailed construction of the apparatus will be described below.
  • the microcomputer 3 contains an EEPROM 4, a resistor 5a of a power-on reset circuit 5 later described, and an n-channel FET 6a of a modulating circuit 6 later described.
  • the EEPROM 4 stores an identification code ⁇ B specific to the corresponding ignition key 1, and also stores later-described functions for generating a cipher code or varying the bit length of the identification code ⁇ B, and optionally a calculating code.
  • the aforementioned functions may be written in a program ROM provided in the microcomputer 3.
  • the bit length of the identification code ⁇ B is preset to a suitable value within a range of, merely for example, 40 to 48 bits.
  • a resonance circuit portion 7 comprises a transponder coil 8 and a resonance capacitor 9 that are connected in parallel between a signal line SL and a ground terminal.
  • the resonance frequency is preset to conform to the frequency band of the carrier wave signal (or power signal) transmitted from a transmission-reception ECU 10 (shown in Fig. 3) installed in the motor vehicle.
  • a power circuit 12 connected to the signal line SL by a resistor 11, rectifies and smoothes the carrier wave signal received by the resonance circuit portion 7 and sends the thus-obtained output to a power terminal VDD of the microcomputer 3.
  • the power circuit 12 comprises a rectifying diode 12a, a smoothing capacitor 12b, a constant-voltage diode 12c and a resistor 12d that are connected as shown in Fig. 1.
  • a detector circuit 13 connected to the signal line SL by the resistor 11, discriminates the enquiry signal supplied together with the carrier wave signal through the resonance circuit portion 7, and sends the discriminated signal to an input port PI of the microcomputer 3.
  • the detector circuit 13 comprises a detector diode 13a, a capacitor 13b, and resistors 13c, 13d that are connected as shown in Fig. 1.
  • the time constant of the detector circuit 13 is preset to a value lower than the charging time constant of the smoothing function portion of the power circuit 12, thus enabling the discrimination of enquiry signals.
  • the modulating circuit 6, comprising the FET 6a, is connected in parallel to the resonance capacitor 9.
  • a modulating capacitor 6b and the source and drain of the FET 6a are connected in series.
  • the impedance of the resonance circuit portion 7 can be changed by turning FET 6a on and off.
  • the reset circuit 5 performs the power-on reset function of holding the microcomputer 3 in a reset state until the level of power supplied to the power terminal VDD of the microcomputer 3 (the output voltage level of the power circuit 12) reaches a predetermined level.
  • the reset circuit 5 comprises a diode 5b, a capacitor 5c and the resistor 5a connected as shown in Fig. 1.
  • An oscillating circuit 14 comprises a resistor 14a and a capacitor 14b, and determines the clock frequency of the microcomputer 3.
  • the functions of the transmitter-receiver device 2 will be described in conjunction with the control by the microcomputer 3.
  • the resonance circuit portion 7 receives a carrier wave signal (power signal as described below) and an enquiry signal including a predetermined random number data AA from the transmission-reception ECU 10, the power circuit 12 rectifies and smoothes the carrier wave signal and outputs the signal to the power terminal VDD of the microcomputer 3.
  • the output power reaches a predetermined level, the reset state held by the reset circuit 5 is canceled, and the microcomputer 3 is switched to an active state.
  • the detector circuit 13 discriminates the enquiry signal received and then outputs it to the input port PI of the microcomputer 3.
  • the thus-activated microcomputer 3 upon receiving the enquiry signal supplied through the detector circuit 13, reads the identification code ⁇ B from the EEPROM 4, enciphers identification code ⁇ B, and further operates the modulating circuit 6 to send back an enciphered answer signal including the thus-changed identification code ⁇ B.
  • the microcomputer 3 is designed to perform the encipherment of answer signals in, for example, the following manner.
  • the microcomputer 3 Upon receiving an enquiry signal, the microcomputer 3 reads a function F, the identification code ⁇ B and, optionally, the calculating code ⁇ C from the EEPROM 4, and carries out the function calculation using the random number code ⁇ A included in the enquiry signal, the identification code ⁇ B and the calculating code ⁇ C as variables, that is, the calculation of F( ⁇ A, ⁇ B, ⁇ C).
  • the calculation result is output as a cipher code.
  • the identification code ⁇ B is subjected to a bit length change as one form of encipherment.
  • the control of the transponder function will be described below with reference to the flowchart shown in Fig. 2.
  • the microcomputer 3 If the microcomputer 3 receives an enquiry signal including the random number data ⁇ A (affirmative determination in step S1), the microcomputer 3 reads the identification code ⁇ B and functions g, h from the EEPROM 4 (step S2), and then performs calculations to change the bit length of the identification code ⁇ B on the basis of the functions g, h and the received random number data ⁇ A in the following steps S3-S5, determining an identification code ⁇ B'. However, in a construction where the functions g, h are stored in the program ROM, the retrieving of the functions g, h is unnecessary.
  • the function g determines which bit of the identification code ⁇ B before the bit length change (hereinafter, referred to as "Xth bit”) corresponds to the first bit (LSB) of the identification code ⁇ B' after the change.
  • the function h determines which bit of the identification code ⁇ B before the bit length change (hereinafter, referred to as "Yth bit”) corresponds to the end bit (MSB) of the identification code ⁇ B' after the change.
  • step S5 Based on the thus-calculated values of X, Y, step S5 extracts a code AXY starting at the Xth bit and ending at the Yth bit of the identification code ⁇ B, and determines the code AXY as a bit length-changed identification code ⁇ B'.
  • the microcomputer 3 After obtaining the bit length-changed identification code ⁇ B', the microcomputer 3 transmits an answer signal including the identification code ⁇ B' (step S6) to ECU 10, and returns to the determining step S1.
  • step S6 performs on-off control of FET 6a of the modulating circuit 6 in a mode corresponding to the bit length-changed identification code ⁇ B', to change the impedance of the resonance circuit portion 7.
  • the received carrier wave signal is modulated in amplitude in a mode corresponding to the bit length-changed identification code ⁇ B'.
  • the change of the impedance of the resonance circuit portion 7 achieved by the modulating circuit 6 is detected by the transmission-reception ECU 10. In this manner, the enciphered answer signal (including the bit length-changed identification code ⁇ B') is sent back to the transmission-reception ECU 10.
  • Fig. 3 schematically illustrates the overall construction of the system by a combination of the functional blocks.
  • An antenna coil 16 is provided around an ignition cylinder 15 of the motor vehicle. When the ignition key 1 is insert in the cylinder 15, the antenna coil 16 is electromagnetically coupled with the transponder coil 8 (see Fig. 1) contained in the ignition key 1.
  • the transmission-reception ECU 10, corresponding to an interrogator according to the invention, of the motor vehicle comprises a microcomputer 17 as a main component.
  • the microcomputer 17 receives on-signals from a key remind switch 19 and an ignition switch 18 provided for the cylinder 15 as well known in the art, via a switch interface 20.
  • the signal received by the antenna coil 16 is inputted to the microcomputer 17 through a receiving circuit 21.
  • the microcomputer 17 is constructed to control the transmission through the antenna coil 16 by the output from a power amplifier 22. This control will be described below.
  • the microcomputer 17 sends signals to and receives signals from an engine control ECU 23 through a serial interface 24.
  • the microcomputer 17 selectively inhibits the engine control ECU 23 from performing an engine starting operation.
  • the microcomputer 17 outputs data to and reads data from an EEPROM 25.
  • the EEPROM 25 serially stores and updates the random number data generated every time a new enquiry signal is to be transmitted to the transmitter-receiver device 2.
  • pre-stored in the EPROM 25 are the same identification code ⁇ B and functions as the identification code ⁇ B and functions stored in the EEPROM 4 of the ignition key 1 provided corresponding to the motor vehicle.
  • the EEPROM 25 stores the same calculating code ⁇ C as stored by the EEPROM 4. The functions may be written in the program ROM provided in the microcomputer 17.
  • the control by the microcomputer 17 of the transmission-reception ECU 10 will be described in conjunction with the functions of related components.
  • the microcomputer 17 When the microcomputer 17 receives on-signals from the key remind switch 19 and the ignition switch 18, that is, when the ignition key 1 is inserted into the cylinder 15 and turned to the on-position (in this state, the antenna coil 16 and the transponder coil 8 of the ignition key 1 are electromagnetically coupled), the microcomputer 17 generates a new random number code ⁇ A by a predetermined calculation for producing random numbers, and stores the random number code ⁇ A into the EEPROM 25, or an internal memory (not shown). The microcomputer 17 also generates a pulse-train enquiry signal including the random number code ⁇ A, and operates the power amplifier 22 to transmit from the antenna coil 16 a predetermined-frequency carrier wave signal and an enquiry signal convoluted therewith including the random number code ⁇ A.
  • the carrier wave signal and the enquiry signal are thus transmitted from the antenna coil 16 to the transmitter-receiver device 2 (see Fig. 1) of the ignition key 1.
  • the microcomputer 3 of the transmitter-receiver device 2 becomes able to be switched to the active state.
  • the microcomputer 3 determines a cipher code or a bit length-changed identification code ⁇ B' by the function calculation using the random number code ⁇ A included in the enquiry signal, and the identification code ⁇ B and the functions and, optionally, the calculating code stored in the EEPROM 4, and sends back an answer signal including the cipher code or the bit length-changed identification code ⁇ B', thus performing the transponder function.
  • the microcomputer 17 performs a decoding operation, more specifically, determines an identification code ⁇ B' by the calculation (corresponding to the operations in step S3-S5 in Fig. 2) using the random number code ⁇ A, the identification code ⁇ B and the functions g, h read from the EEPROM 25, and compares the identification code ⁇ B' with the identification code ⁇ B' included in the answer signal from the transmitter-receiver device 2. If the two identification codes do not agree, that is, if the received answer signal is not proper, the microcomputer 17 inhibits the engine control ECU 23 from starting the engine of the motor vehicle. In a construction where the functions g, h are stored in the program ROM, the retrieving of the functions g, h is unnecessary.
  • the microcomputer 17 permits the engine control ECU 23 to start the motor vehicle engine.
  • the starting of the motor vehicle engine by the engine control ECU 23 is allowed if the ignition cylinder 15 receives the correct ignition key 1 so that the bit length-changed identification codes ⁇ B' generated based on the identification codes ⁇ B and other parameters agree with each other.
  • the embodiment thus performs an immobilization function.
  • the embodiment improves security and, therefore, the detection against theft of the motor vehicle. Since the transmitter-receiver device 2 changes the bit length of the pre-stored identification code ⁇ B on the basis of the random data ⁇ A included in the enquiry signal and the functions g, h, and sends back an enciphered answer signal including the thus-changed identification code ⁇ B', this embodiment achieves the encipherment of answer signals without complicating the construction.
  • this embodiment enhances security with regard to the answer signal from the transmitter-receiver device 2, compared with the conventional method in which a plurality of identification codes sequentially cycle.
  • the embodiment enables the setting of various cryptographic procedures, eliminating the need to prepare different hardware constructions for different transmitter-receiver devices 2. As a result, the working efficiency in production can be improved and production costs can be reduced.
  • the transponder function is controlled by the program installed in the microcomputer 3, the protocol of the communications between the transmitter-receiver device 2 and transmission-reception ECU 10 will not be fixed to a single protocol. Thus the embodiment increases the degrees of freedom in design.
  • Fig. 4 illustrates a second embodiment of the invention that achieves advantages similar to those of the first embodiments. Only the features of the second embodiment that distinguishes it from the first embodiment will be described below.
  • the second embodiment differs from the first embodiment in the bit length changing control of identification code ⁇ B by the microcomputer 3 of the transmitter-receiver device 2.
  • the flowchart of Fig.4 illustrates the control.
  • step S1 when the microcomputer 3 receives an enquiry signal including random number data ⁇ A (affirmative determination in step S1), the microcomputer 3 reads the identification code ⁇ B and the function i from the EEPROM 4 (step S2'), and then performs calculations to change the bit length of the identification code ⁇ B on the basis of the function i and the received random number data ⁇ A in the following steps S3'-S5', determining an identification code ⁇ B'.
  • step S5' Based on the thus-calculated value of the bit length Z, step S5' extracts a code A1Z starting at the first bit (LSB) and ending at the Zth bit of the identification code ⁇ B, and determines the code A1Z as an identification code ⁇ B' after the bit length change.
  • the identification code ⁇ B' may be determined by extracting a code over the MSB and the less significant bits down to the Zth bit in the descending order.
  • the microcomputer 3 After obtaining the identification code ⁇ B', the microcomputer 3 transmits an answer signal including the identification code ⁇ B' (step S6), and returns to the determining step S1.
  • Fig. 5 illustrates a third embodiment of the invention that is modified from the first embodiment. The features of the third embodiment distinguishing it from the first embodiment will be described below.
  • the third embodiment is characterized by enciphering the identification code ⁇ B by a predetermined cryptosystem, prior to the bit length changing control of the identification code ⁇ B by the microcomputer 3 of the transmitter-receiver device 2.
  • the enciphered identification code is then subjected to the bit length changing control.
  • the flowchart of Fig. 5 illustrates this control operation.
  • step R1 when the microcomputer 3 receives an enquiry signal including random number data ⁇ A (affirmative determination in step R1), the microcomputer 3 reads the identification code ⁇ B and the functions, f, g, h from the EEPROM 4 (step R2), and then performs calculations in the following steps R3-R5 to change the bit length of the identification code ⁇ B on the basis of the functions f, g, h and the received random number data ⁇ A, determining an identification code ⁇ B'.
  • the function f is a function for enciphering the identification code ⁇ B.
  • the conventional rolling or cyclical code enciphering method may be employed as a function f.
  • the function g determines which bit of the cipher code Amax (the Xth bit) corresponds to the initial bit (LSB) of the identification code ⁇ B' after the bit length change.
  • the function h determines which bit of the cipher code Amax ("the Yth bit") corresponds to the end bit (MSB) of the identification code ⁇ B' after the bit length change.
  • step R6 Based on the thus-calculated values of X, Y, step R6 extracts a code AXY starting at the Xth bit and ending at the Yth bit of the cipher code Amax, and determines the code AXY as an identification code ⁇ B' after the bit length change.
  • the microcomputer 3 After obtaining the identification code ⁇ B', the microcomputer 3 transmits an answer signal including the identification code ⁇ B' (step R7), and returns to the determining step R1.
  • this embodiment achieves advantages similar to those of the first embodiment.
  • this embodiment performs double-encipherment of the identification code ⁇ B included in an answer signal, it enhances security regarding the answer signal from the transmitter-receiver device 2.
  • Fig. 6 illustrates a fourth embodiment of the invention that achieves advantages similar to those of the third embodiment. The features of the fourth embodiment that distinguishes it from the third embodiment will be described below.
  • the fourth embodiment differs from the third embodiment in the bit length changing control of the identification code ⁇ B by the microcomputer 3 of the transmitter-receiver device 2.
  • the flowchart of Fig.6 illustrates the control.
  • the microcomputer 3 If the microcomputer 3 receives an enquiry signal including the random number data ⁇ A (affirmative determination in step R1), the microcomputer 3 reads the identification code ⁇ B and the functions f,_@i from the EEPROM 4 (step R2'), and then performs calculations in the following steps R3, R4' and R6' to change the bit length of the identification code ⁇ B on the basis of the functions f, i and the received random number data ⁇ A, determining an identification code ⁇ B'. However, in a construction where the functions f, i are stored in the program ROM, the retrieving of the functions f, i is unnecessary.
  • the function f is a function for enciphering the identification code ⁇ B, as in the third embodiment.
  • Step R3 performs the calculation of a function based on both the random number data ⁇ A and the identification code ⁇ B as variables, to encipher the identification code ⁇ B into a cipher code Amax of a predetermined bit length (for example, 40-48 bits)
  • step R6' Based on the thus-calculated value of the bit length Z, step R6' extracts a code A1Z starting at the first bit (LSB) and ending at the Zth bit of the cipher code Amax, and determines the code A1Z as an identification code ⁇ B' after the bit length change.
  • the identification code ⁇ B' may be determined by extracting a code over the MSB and the less significant bits down to the Zth bit in the descending order.
  • the microcomputer 3 After obtaining the identification code ⁇ B', the microcomputer 3 transmits an answer signal including the identification code ⁇ B' (step R7), and returns to the determining step R1.
  • the EEPROM 4 need only store at least one of the identification code AB and the function.
  • One of the identification code ⁇ B and the function may be fixed.
  • the transmitter-receiver device 2 enciphers the identification code ⁇ B using the function f and then changes the bit length of the thus-obtained cipher code Amax, it is also possible to change the bit length of the identification code ⁇ B and then encipher the bit length-changed identification code using the function f.
  • the transmission-reception ECU 10 performs decoding by calculating an identification code ⁇ B' by calculation based on the random number data ⁇ A, identification code ⁇ B and functions stored in the EEPROM 25 in a calculation manner similar to that of the microcomputer 3 of the transmitter-receiver device 2, and by comparing the thus-determined identification code ⁇ B' with the identification code ⁇ B' included in the answer signal from the transmitter-receiver device 2.
  • the decoding may be performed by calculating an identification code ⁇ B from the identification code ⁇ B' included in the answer signal and then comparing the calculated identification code ⁇ B with the random number data ⁇ A stored in the EEPROM 25.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Lock And Its Accessories (AREA)

Claims (6)

  1. Dispositif émetteur-récepteur (1, 2) qui reçoit un signal d'alimentation et un signal d'interrogation depuis une source externe, et répond au signal d'interrogation en envoyant en retour un signal de réponse sur la base d'un code d'identification pré stocké, comprenant
       un circuit de résonance (7), capable de recevoir des signaux électromagnétiques ;
       un circuit d'alimentation (12) pour rectifier et lisser un signal d'alimentation fourni au moyen du circuit de résonance depuis une antenne externe lorsque l'antenne externe est couplée de façon électromagnétique avec le circuit de résonance, le circuit d'alimentation ayant une première constante de temps ;
       un micro-ordinateur (3) alimenté par une sortie depuis le circuit d'alimentation ;
       un circuit détecteur (13), ayant une deuxième constante de temps qui est inférieure à la première constante de temps du circuit d'alimentation, et qui, lorsque le circuit de résonance est couplé de façon électromagnétique avec l'antenne externe, différencie un signal d'interrogation fourni en même temps qu'un signal d'alimentation au moyen du circuit de résonance depuis l'antenne externe, et sort le signal d'interrogation vers le micro-ordinateur ;
       un moyen de stockage (4) pour stocker un code d'identification ; et
       un circuit de modulation (6) qui fonctionne pour transmettre le signal de réponse en changeant une impédance du circuit de résonance ;
       dans lequel lors de la réception du signal d'interrogation au moyen du circuit détecteur (13), le micro-ordinateur (3) génère un code d'identification modifié en changeant la longueur de bit du code d'identification lu à partir du moyen de stockage (4) sur la base d'une donnée reçue fondée sur un nombre aléatoire, ensemble avec le signal d'interrogation, au moyen du circuit de résonance (7) et d'un calcul prédéterminé, et commande l'émission d'un signal de réponse comportant le code d'identification ainsi modifié au moyen du circuit de résonance (7) en faisant fonctionner le circuit de modulation (6) dans un mode correspondant au code d'identification modifié.
  2. Dispositif émetteur-récepteur (1, 2) selon la revendication 1, dans lequel le moyen de stockage (4) comprend une mémoire rechargeable non volatile à données rechargeables de telle façon que l'on puisse changer le code d'identification.
  3. Système d'émission réception comprenant :
    un dispositif de commande de mise en marche (10) pour commander l'opération de mise en marche d'un appareil qui transmet un signal d'interrogation et un signal d'alimentation ; et
    un dispositif émetteur-récepteur (1, 2) selon la revendication 1,
    le dispositif de commande de mise en marche (10) transmettant du nombre aléatoire de données en même temps que le signal d'interrogation, et déterminant si le signal de réponse envoyé en retour depuis le dispositif émetteur-récepteur (1, 2) correspond à une réponse prédéterminée au moyen d'un calcul basé sur du nombre aléatoire de données et le code d'identification stocké dans le dispositif de commande de démarrage (10), et
    le dispositif émetteur-récepteur (1, 2) changeant la longueur de bit du code d'identification stocké sur la base du nombre aléatoire de données provenant du dispositif de commande de mise en marche (10) et d'un calcul prédéterminé, et envoyant en retour un signal de réponse comprenant le code d'identification ainsi changé.
  4. Système d'émission réception selon la revendication 3, dans lequel le dispositif émetteur-récepteur (1, 2) crypte le code d'identification stocké au moyen d'un système de cryptage prédéterminé, change la longueur de bit du code d'identification crypté sur la base du nombre aléatoire de données à partir du dispositif de commande de mise en marche (10) et du calcul prédéterminé, et envoie en retour un signal de réponse comprenant le code ainsi changé.
  5. Système d'émission réception selon la revendication 3, dans lequel le dispositif émetteur-récepteur (1, 2) change la longueur de bit du code d'identification sur la base du nombre aléatoire de données provenant du dispositif de commande de mise en marche (10) et du calcul prédéterminé, crypte le code d'identification ainsi changé au moyen d'un système de cryptage prédéterminé, et envoie en retour un signal de réponse comprenant le code d'identification crypté.
  6. Procédé pour authentifier le fonctionnement de démarrage d'un appareil, comprenant les étapes de :
    (a) fourniture d'un signal d'interrogation comprenant un nombre aléatoire de données et un signal d'alimentation et les transmettant au moyen d'une antenne d'un dispositif de commande de mise en marche (10) ;
    (b) réception desdits signal d'interrogation, signal d'alimentation et nombre aléatoire de données dans un dispositif émetteur-récepteur (1, 2) selon la revendication 1, ledit signal d'alimentation, alimentant le fonctionnement dudit dispositif émetteur-récepteur (1, 2) ;
    (c) conversion d'un code d'identification stocké dans ledit dispositif émetteur-récepteur (1, 2) en un code d'identification modifié, en changeant la longueur de bit du code d'identification sur la base dudit nombre aléatoire de données et d'un calcul prédéterminé ;
    (d) transmission du code d'identification modifié audit dispositif de commande de mise en marche (10) ;
    (e) authentification du dispositif émetteur-récepteur, en comparant l'information d'identification modifiée aux données dans le dispositif de commande de mise en marche (10).
EP96118404A 1995-11-16 1996-11-15 Système de transmission et réception Expired - Lifetime EP0774673B1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP298087/95 1995-11-16
JP29808795 1995-11-16
JP29808795A JPH09139985A (ja) 1995-11-16 1995-11-16 送受信装置
JP30261195 1995-11-21
JP302611/95 1995-11-21
JP30261195A JPH09149480A (ja) 1995-11-21 1995-11-21 送受信システム

Publications (3)

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EP0774673A2 EP0774673A2 (fr) 1997-05-21
EP0774673A3 EP0774673A3 (fr) 2000-07-12
EP0774673B1 true EP0774673B1 (fr) 2004-08-18

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EP (1) EP0774673B1 (fr)
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EP1688889B1 (fr) * 2005-02-04 2017-06-21 SMARTRAC TECHNOLOGY Wehnrath GmbH Procédé de communication et de contrôle de données d'authentification entre un dispositif portable à transpondeur et une unité de lecture d'un véhicule
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Publication number Publication date
EP0774673A2 (fr) 1997-05-21
DE69633165T2 (de) 2005-08-11
EP0774673A3 (fr) 2000-07-12
DE69633165D1 (de) 2004-09-23
US5844990A (en) 1998-12-01

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